Concurrent Speaker Detection (CSD), the task of identifying the presence and overlap of active speakers in an audio signal, is crucial for many audio tasks such as meeting transcription, speaker diarization, and speech separation. This study introduces a multimodal deep learning approach that leverages both audio and visual information. The proposed model employs an early fusion strategy combining audio and visual features through cross-modal attention mechanisms, with a learnable [CLS] token capturing the relevant audio-visual relationships. The model is extensively evaluated on two real-world datasets, AMI and the recently introduced EasyCom dataset. Experiments validate the effectiveness of the multimodal fusion strategy. Ablation studies further support the design choices and the training procedure of the model. As this is the first work reporting CSD results on the challenging EasyCom dataset, the findings demonstrate the potential of the proposed multimodal approach for CSD in real-world scenarios.